I thought Bento was about the skeleton. Is Bento Hair a gimmick, or is it actually different from regular mesh-hair?
When you're talking about 3d animated objects, skeletons are a common method of animation. Anything intended to move can have a skeleton; trees, doors, cars, whatever. It's not just limited to human and animal bodyparts.
What Bento introduced was a range of additional bones (the individual parts of a skeleton that can be animated), over and above the pre-existing ones. These extra bones are available for mesh attachments and can be used for just about anything you can come up. Hair is honestly, one of the less out there applications.